In image signals, upper and lower limits of effective amplitude levels are defined based on respective signal formats, and if a signal deviates from a region between the upper and lower limits (gamut as the whole region that can be treated as the effective image signal), it becomes unable to accurately reproduce color.
Therefore, as a monitor for displaying images, there has been existed the one having the function of detecting a gamut error of an input image signal. In such conventional monitor, occurrence of a gamut error has been notified to the user only by one kind of means such that in a frame in which a gamut error has been detected, a zebra pattern (stripe pattern) is superimposed to be displayed in a pixel position where the gamut error has been detected, of an image to be screen-displayed in a monitor.
Also, in the literature, as the technology having a feature in the gamut error notifying means, there have been proposed a technology that has made the amount and direction of a gamut error visibly easy to understand by displaying input image signals as waveforms (Pareto display) (for example, Japanese Unexamined Patent Application Publication No. Hei6-303648 published by Japanese Patent Office), and a technology to display the input image signal in monochrome and the portion of a pixel position where a gamut error has been detected in color using the color corresponding to the error state (for example, Japanese Unexamined Patent Application Publication No. 2005-12802 published by Japanese Patent Office). However, even in the technologies described in those literatures, only one kind of gamut error notifying means is provided.
Meanwhile, in the conventional gamut error notifying means as described above, there exist good points and bad points that are peculiar to them. For example, in the notifying means displaying a zebra pattern, there is a good point that the original image can be avoided from being hidden so much on the screen, but on the other hand, there exists a bad point that when the occurrence region of a gamut error is small, the display region of the zebra pattern also becomes small, so that it is easy to be overlooked (particularly, in moving images, because the display position of the zebra pattern changes for each frame, it is easy to be overlooked).
And, what the user desires to prioritize when monitoring gamut errors (for example, to prioritize not hiding the original image so much, or to prioritize making notification of a gamut error not to be easily overlooked even at the expense of hiding the original image) varies from one user to another, and may differ even for the same user depending on the purpose of monitoring gamut errors.
However, in the conventional monitors and technologies described in conventional literatures, because only one kind of gamut error notifying means is provided, it was not always possible to monitor gamut errors in the manner the user desires.
Further, with respect to the condition for deactivating the notification after notifying occurrence of a gamut error also, there exist good and bad points peculiar to respective conditions. For example, under the condition that notification is deactivated in a frame in which the gamut error has become undetectable (that is, notification is carried out only in the frame in which the gamut error has been detected), there exists a good point that it can be clearly recognized whether or not the gamut error is occurring in the present frame, but on the other hand, there exists a bad point that when the occurrence of a gamut error has been in an instance, the user is easy to overlook the notification.
Also, what condition the user desires as the condition for deactivating notification of a gamut error varies from one user to another, and even for the same user, the condition may differ depending on the purpose of monitoring gamut errors.
Consequently, the present invention addresses providing a gamut error notifying device enabling the user to selectively set the gamut error notifying means and the condition for deactivating notification of a gamut error.